1. Field
The invention relates to an automatic pipetting device.
2. Background
The invention relates to an automatic pipetting device in which only one pipetting needle is available with its own appropriate metering and transport means for the pipetting needle, the pipetting needle being connected to a metering syringe by a first tube and a first T-connection.
In the area of automatic analysers, for example those used for performing chemical analyses clinically, automatic pipetting devices of the above kind are known which usually form part of such an analyser and which serve for metering and transferring liquid samples or specimens and reagents between various containers, for example, from a reagent container or sample or specimen container into a measuring dish where a mixture of sample or specimen and reagent is formed and is analysed in the analyser. Known pipetting devices of this kind comprise a transport means which moves the pipetting needle into a number of pipetting positions and, between the pipetting operations, into a cleaning position, where the pipetting needle is cleaned with a suitable liquid, so that each pipetting operation may be carried out with a clean pipetting needle free from residues of any previous pipetting operation.
In the case of larger analysers, two independent pipetting devices, for example, are provided each with its own appropriate metering and transport means for the pipetting needles. This enables either pipetting needle to be used alternately while the other pipetting needle is being cleaned. Since the cleaning of one of the pipetting needles and the use of the other pipetting needle for performing a pipetting operation take place simultaneously, the duration of the working cycle of the pipetting device is not lengthened by the interval for cleaning the pipetting needle, that is, the duration of the interval required for cleaning the pipetting needle does not affect the duration of the working cycle of the pipetting devices of the analyser and therefore has no effect on the duration of the analyser working cycle. The sample or specimen throughput, that is, the number of samples or specimens which can be examined with the analyser per unit of time, is therefore independent of the duration of the interval required for cleaning the pipetting needle.
In the case of smaller analysers, with the aim of minimum apparatus complexity, there is usually just one pipetting device available, that is, just one pipetting needle with its metering and transport means. One consequence of this simplification of the analyser is that the interval required for cleaning the pipetting needle must be integrated into the analyser working cycle. The latter thus becomes longer and sample or specimen throughput becomes reduced.